Other Financial Data - Schedule of Allowance for Doubtful Accounts (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of period	$ 62	$ 70	$ 58	$ 74
Provision charged to Other general expenses	6	3	12	11
Accounts written off, net of recoveries	(4)	(13)	(7)	(22)
Foreign currency translation	0	5	1	2
Balance at end of period	$ 64	$ 65	$ 64	$ 65